Very little connected to Margaret Thatcher's legacy comes without an argument.

The claim by the bishop of London in his funeral address that the former scientist was "part of the team that invented Mr Whippy ice-cream" is no exception.

The New Scientist reported in July 1983, as Thatcher was elected a fellow of the Royal Society body of scientists, that she had worked "developing emulsifiers for ice-creams for Joe Lyons from 1949-51".

The Washington Post, in the wake of her death last week, claimed she "helped invent ice-cream as we know it", adding that her efforts as part of the Lyons team to create a cheap, airy ice-cream were "one aspect of Margaret Thatcher's legacy we can all feel unequivocally good about".

Mr-Whippy-style soft-serve ice-cream originated in the US about a decade before Thatcher worked at J Lyons, it reports. When soft-serve arrived in the UK, J Lyons was indeed at the forefront – but it had teamed up with the US ice-cream behemoth Mister Softee and operated franchises under that name.

Thatcher was a food research scientist at J Lyons but, as a Royal Society article noted in May 2011, the details of her work there are sketchy. She reportedly worked on the quality of cake and pie fillings as well as ice-cream, and researched saponification (soap-making).

The article reports: "An oft-told anecdote in British left circles associates Thatcher with the invention of soft ice-cream, which added air, lowered quality and raised profits. Lyons certainly worked on this new product, but there is no firm evidence that Thatcher directly assisted in its invention."